While it would be great if each country could take care of its own people, some will inevitably lack the resources to do so, since natural resources are not distributed equally across the globe. To me this is the same mentality that fosters and excuses income inequality WITHIN countries, this idea that "oh if that person just worked harder they wouldn't be in poverty", and "why should I pay for welfare and food stamps, those people are there by choice". At least, those are the opinions of the political right here int he US. Would you be in favor of cutting all social services in UK? To me, this idea of "every country for itself" is no different than "every man for himself". After all, countries do not exist in a vacuum, we are all part of a global economy and a single entity - humanity.
Do I contribute to aid charities? Generally not - I do not have an infinite amount of money to give away, and my priorities are wildlife/nature conservation, and occasionally local issues. But I could not, in good conscience, advocate the abandonment of such aid programs. Sure, I agree that controlling population growth is the single most effective way to halt habitat and biodiversity loss, but if I wouldn't be willing to sacrifice myself or my loved ones to the cause, what right do I have to demand that others be forced do so? If you're going to suggest that, then why stop there, why not suggest the government of your own country remove all federal funds for health care - you don't want to be paying to keep people alive and reproducing, right, when their deaths could help reduce the population? Somehow I suspect not. Education and reform are the way to go.